Adsorption capacity of Punica granatum L. peels towards lead Pb(II) and antioxidant activities of its extracts

Abstract

The first part of this study aimed to characterize the pomegranate peels powder of both varieties via FT-IR,point of zero charge and surface functional groups analysis and to evaluate the adsorption capacities of these biomasses towards leads ions using batch method and the potential of using them for the treatment of industrial wastewater polluted with lead.The effect of some experimental parameters on the adsorption capacities was studied.Isotherms and adsorption kinetics have also been studied and treated with different mathematical models.The regeneration of the red and yellow pomegranate peels powder after adsorption was also assessed. The second part of this work aimed to determine the total polyphenols,flavonoids,condensed tannins and anthocyanins content in the aqueous, methanolic and ethanolic peels extracts of the red and yellow Punica granatum L. varieties and to evaluate their antioxidant activity in vitro.Results showed the richness of both biomasses with acidic functional surface groups.The study of different factors on the adsorption process showed that the adsorption capacity increases with pH until pH6,contact time and initial metal concentration and it decreases with increasing the biosorbent dose.For the adsorption isotherms of lead onto the red and yellow pomegranate peels powder,the Langmuir model was more fitting with an adsorption capacity(Qmax)of 90and 89.25 mg.g-1, respectively.The kinetic data suited better with the pseudo-second order model.Lead acidic desorption was efficient ,with a high percentage of recovery.The findings indicate that these biomasses can be utilized as biosorbents for lead removal from aqueous solutions with the possibility of their reuse.The results also showed that the methanolic and ethanolic peels extracts of red and yellow varieties are richer in polyphenols,flavonoids,condensed tannins and anthocyanins than the aqueous ones.All the tested extracts have shown powerful scavenging activities towards DPPH and ABTS radicals and an appreciable antioxidant inhibiting effects with the reducing power, iron chelation and β-carotene tests.